The traditional implantable cardiac pacemaker includes a pulse generator device to which one or more flexible elongate lead wires are coupled. The device is typically implanted in a subcutaneous pocket, remote from the heart, and each of the one or more lead wires extends therefrom to a corresponding electrode, coupled thereto and positioned at a pacing site, either endocardial or epicardial. Mechanical complications and/or MRI compatibility issues, which are sometimes associated with elongate lead wires and well known to those skilled in the art, have motivated the development of implantable cardiac pacing devices that are wholly contained within a relatively compact package, the entirety of which is configured for implant in close proximity to the pacing site. FIG. 1 is a schematic that shows a potential cardiac implant site for such a device within an appendage 102 of a right atrium RA. An implanting physician may employ a delivery tool 400 to deploy a relatively compact medical device to the site, for example, after maneuvering tool 400, with the device loaded therein, up through the inferior vena cava IVC and into the right atrium RA. Although some suitable configurations of a fixation component for such an implantable medical device have been disclosed, for example, in a co-pending and commonly assigned U.S. patent application having the Ser. No. 14/518,211, there is a need for new configurations of fixation components that can enhance the stability of fixation.